NHS staff responsible for the “terrible” care of patients at Stafford Hospital could face prosecution for wilful neglect or manslaughter, the head of the inquiry into failings of care suggested today.

Robert Francis QC, who conducted the official inquiry into Mid Staffordshire NHS Trust, said people should be “held to account” where it was possible to do so.

However, he warned that some of the “terrible things” that happened at the hospital didn’t “necessarily fit easily into a criminal category”.

Mr Francis said that while his inquiry did not blame individuals that did not mean that those who worked and managed health care in Staffordshire should not be held to account.

He said the terms of his inquiry were to examine actions - or inactions - of organisations rather than individuals against a “background of the most appalling” care provided to large numbers of patients at Stafford Hospital.

But he added: “I do not believe that this report exonerates people at all, I do urge those who have not done so to read the accounts given of the history in the various chapters about the organisations, where I set out in detail what individuals have done and what they have not done, what letters they got and their reaction to these letters.

“Others may disagree but I personally believe that is the useful contribution a public inquiry can make in this situation.”

His comments are likely to be seized upon by critics of Sir David Nicholson, head of the NHS Commissioning Board, who was in charge of the Strategic Health Authority overseeing Mid Staffordshire at the time of the scandal.

Some, including in private some cabinet ministers, believe Sir David should step down over his role. The organisation that he ran was criticised in the report.

But Mr Francis said effectively putting people on trial by making one of the inquiry terms of reference that of identifying individuals responsible would have resulted in a number of “unfortunate” results.

“You cannot try people without it being fair,” he told MPs on the House of Commons health select committee.

“I personally think that would have had a number of unfortunate results...the first would have been the duration and extent of the inquiry.

“Every single person involved would have instructed a lawyer, every single person would have to have been a core participant.

“I know some people have criticised the length of my inquiry but I would have been running this inquiry for years - the lessons would not have been learned but perhaps the most important point is that I don't think we would have found out as much as we did.”

Mr Francis said his job had been to find out from as many people as possible what had happened and to build up a picture of events at Stafford Hospital and then to draw lessons for the future.

“Clearly one of these lessons is that there is insufficient accountability in this system and it is for that reason that I make a number of recommendations in that regard,“ he said.

Mr Francis said he had witnessed a ”tsunami of anger“ directed towards the NHS over the absence of consideration of the impact of actions upon patients.

”I have not said that individuals should not be held to account, clearly they should be where possible,“ he told MPs.

The public inquiry report by Mr Francis called for a ”zero tolerance“ approach to poor standards of care in the health system. It said the NHS had failed to protect patients at the hospital, regulatory agencies failed to communicate and there was ”too great a degree of tolerance of poor standards.“

The trust failed to tackle an insidious negative culture” including a tolerance of poor care standards and had a culture of “self promotion” rather than critical analysis and openness, his report found.

The public inquiry was ordered after a separate report revealed that between 400 and 1,200 more people died than expected at Stafford Hospital over a four year period between 2005 and 2009.

Patients were left for hours sitting in their own faeces, food and drink was left out of reach and hygiene was so poor that relatives had to clean toilets themselves.